VOLUME XXIV 



THE 



NUMBER 5 



Journal of Geology 



A Semi-Quarterly 



Edited By 

 thomas c. chamberlin and rollin d. salisbury 



With the Active Collaboration of 

 SAMUEL W. WILLI3TON, Vertebrate Paleontology ALBERT. JOHANNSEN, Petrology 



STUART WELLER, Invertebrate Paleontology ROLLIN T. CHAMBERLIN, Dynamic Geology 



ALBERT D. BROKAW, Economic Geology 



SIR ARCHIBALD GEIKIE, Great Britain 



CHARLES BARROIS, France 



ALBRECHT PENCK, Germany 



HANS REUSCH. Norway 



GERARD DeGEER, Sweden 



T. W. EDGEWORTH DAVID, Australia 



BAILEY WILLIS, Leland Stanford Junior University 



GROVE K. GILBERT, Washington, D.C. 



CHARLES D. WALCOTT, Smithsonian Institution 



HENRY S. WILLIAMS, Cornell University 



ASSOCIATE EDITORS 



JOSEPH P.IDDINGS, Washington, D.C. 

 JOHN C. BRANNER, Leland Stanford Junior University 

 RICHARD A. F. PENROSE, Jr., Philadelphia, Pa. 

 WILLIAM B. CLARK, Johns Hopkins University 

 WILLIAM H. HOBBS, University of Michigan 

 FRANK D. ADAMS, McGill University 

 CHARLES K. LEITH, University of Wisconsin 

 WALLACE W. ATWOOD, Harvard University 

 WILLIAM H. EMMONS, University of Minnesota 

 ARTHUR L. DAY, Carnegie Institution 



JULY-AUGUST 1916 



THE GEOLOGICAL SIGNIFICANCE AND GENETIC CLASSIFICATION OF ARKOSE 



DEPOSITS ----------- -Donald C. Barton 417 



AN UNUSUAL FORM OF VOLCANIC EJECTA - - - - - Wallace E. Pratt 45° 



RIPPLE-MARKS IN OHIO LIMESTONES ----- Charles S. Prosser 456 

 THE RELATIONSHIPS OF THE OLENTANGY SHALE AND ASSOCIATED DEVONIAN 



DEPOSITS OF NORTHERN OHIO C. R. Stauffer 476 



EVOLUTION OF THE BASAL PLATES IN MONOCYCLIC CRINOIDEA CAMERATA. I 



Herrick E. Wilson 488 



VARIATIONS OF GLACIERS. XX ------ Harry Fielding Redd 511 



REVIEWS - '".,.-.. 5I5 



RECENT PUBLICATIONS 5 19 



THE UNIVERSITY OF CHICAGO 



CHICAGO, ILLINOIS, U.S.A. 



PRESS 



Agents 



THE CAMBRIDGE UNIVERSITY PRESS, London and Edinburgh 



KARL W. HIERSEMANN, Leipzig 



THE MARUZEN-KABUSHIKI-KAISHA, Tokyo, Osaka, Kyoto 



THE MISSION BOOK COMPANY, Shanghai 



